“Soul sleep” is a belief that after a person dies, his/her soul “sleeps” until the resurrection and final judgment. The concept of “soul sleep” is not biblical. When the Bible describes a person “sleeping” in relation to death (Luke 8:52; 1 Corinthians 15:6), it does not mean literal sleep. Sleeping is just a way to describe death because a dead body appears to be asleep. The moment we die, we face the judgment of God (Hebrews 9:27). For believers, to be absent from the body is to be present with the Lord (2 Corinthians 5:6-8; Philippians 1:23). For unbelievers, death means everlasting punishment in hell (Luke 16:22-23).
Until the final resurrection, though, there is a temporary heaven—paradise (Luke 23:43; 2 Corinthians 12:4) and a temporary hell—Hades (Revelation 1:18; 20:13-14). As can be clearly seen in Luke 16:19-31, neither in paradise nor in Hades are people sleeping. It could be said, though, that a person’s body is “sleeping” while his soul is in paradise or Hades. At the resurrection, this body is “awakened” and transformed into the everlasting body a person will possess for eternity, whether in heaven or hell. Those who were in paradise will be sent to the new heavens and new earth (Revelation 21:1). Those who were in Hades will be thrown into the lake of fire (Revelation 20:11-15). These are the final, eternal destinations of all people—based entirely on whether or not a person trusted in Jesus Christ for salvation.
Present-day defenders of soul sleep include the Seventh Day Adventist church, Jehovah’s Witnesses, Christadelphians, and others.